Book excerpt: Provides a stimulating and substantive intellectual history of social science and development theories, helping towards an understanding of development theory and development problems in the three worlds. Describes early, primarily European, theories on development and how they were enriched, challenged and transformed in response to Third World realities. It moves on to discuss how this body of theory, Marxist and non-Marxist, has become increasingly relevant for understanding structural development problems, which are occurring in the rich world, and the relationships between development theory and the mainstream social sciences.